Color television



April 1949. P. c. GOLDMARK 2,466 02fi COLOR TELEVISION Filed Nov. 27, 1945 3 Sheets-Sheet 1 INVENTOR Pefi'Yr'GGa/Jmar-K ATTORNEYS April 5, 1949. P. c. GOLDMARK COLOR TELEVISION Filed Nov. 27, 1945 3 Sheets-Sheet 2 INVENTOR 1/4, 11/ IIII/IIIIII/IIIIIIIIII/{M BY Rm -c. Go/Jmqrk m, V

ATTORNEYS April 5;, M E-9. P. c. GOLDMARK 2,465,021

COLOR TELEVISION Filed Nov. 27, 1945 3 Sheets-$heet 5 llll " miii. n fllhlii INVENTOR gcyr C. Go/a' na H? 5104410, MPM

ATTORNEYS Patented Apr. 5, 1949 COLOR TELEVISION Peter. C.

Goldmark, New Canaan, Conn., assignor to Columbia Broadcasting System, Inc., New

York,

N. Y., a corporation of New York Application November 27, 1945, Serial No. 631,064

25 Claims.

This invention relates broadly to a rotatable color filter device useful in television, and, more particularly, to the combination of an electronic scanning device and a rotatable color filter which permits conveniently of either color or so-called black and white picture transmission by a television camera or film-scanner, and, optionally at a television receiver, the viewing of television pictures in color or in black and white of pictures transmitted in color and the viewing directly of pictures transmitted in black and white.

The principal object of the invention is to provide a rotatable color filter in the general form of a disk, cylinder, cone or the like in operative optical relation with an electronic scanning device and wherein the light path to and from the device may be modulated by the moving color filters, or, upon bringing the filters to rest, the light path will become unobstructed by the filters and pass white light exclusively.

To the ends described and in accordance with the invention, a preferred embodiment comprises a rotatable color filter of one of the forms above described having a movable portion or a movable segment of appropriate size in optical relation with the image area of an associated transmitting or receiving electron tube scanning device. The construction and mechanical arrangement of the rotatable filter is such that when it is brought to rest the movable segment or portion is moved automatically or otherwise from the light path to and from the image area of the tube so as not to obstruct the same.

The invention may be embodied readily in the several forms of rotatable filter arrangements shown in my prior Patents Nos. 2,304,081 and 2,317,989, and in my pending application Serial No. 370,008, and also in prior patents of others Nos. 2,319,803, 2,319,804, 2,319,805 and 2,339,256, all assigned to my assignee, to enable the transmission or reception, as the case may be, of black and white pictures unobstructed by the color filter. Thus a color television camera or may be employed at will color or black and white" pictures. color television receiver may be made stantially instantly for the reception duction in black and white being transmitted in One embodiment scanning device. When so stopped a movable segment thereof is rotated to a position in which the light path to and from the image area of the device is not obstructed. In this way, the color filter does not interfere with the scanning operation and "black and white transmission may be effected with a television camera or film scanner, as the case may be. Likewise at areceiver, the color filter would not obstruct the light path and thus permit viewing of pictures in "black and white.

Although the invention is useful in television cameras, film scanners and receivers generally, it is particularly advantageous in its application to home color television receivers employing rotatable color filters which are operated by those less skilled than the operators of television transmitting apparatus. Since the operation of the rotatable filter of the invention in a television receiver may be made substantially automatic, its use in home color television receivers contributes greatly to the enjoyment of television reception.

The rotatable color filter of the invention may be arranged to operate in substantial dynamic balance with its axis in any plane. Thus, it may be arranged for operation with the axis of rotation in a horizontal or in a vertical plane. Depending upon the orientaton of the axis, stops. catches, gravity, springs or any other like expedient may be employed to arrest the rotation of the filter at a predetermined position with relation to its associated scanning device, and to move a segment or portion thereof to a position so that the filter no longer obstructs the light path to and from the image area.

The invention will be more readily understood by reference to the drawings and the following description thereo In the drawings:

Fig. 1 illustrates an arrangement of a cathoderay tube and color filter with movable segment as in a television receiver, in accordance with the invention;

Fig. 2 is a front view of the arrangement of Fig. 1 with the color filter at rest, the movable segment having been rotated out of the light path to expose the luminescent screen of the cathode-ray tube to direct view;

Fig. 3 is a front view of the arrangement of Fig. 1, similar to Fig. 2, but with the filter as in rotation, the movable segment having been rotated to its operative position;

Fig. 4 is a schematic illustration of the arrangement for deenergizing the driving motor and arresting rotation of the filter shaft and filter in a predetermined position in relation to the screen of the cathode-ray tube, as shown in Fig. 2;

Fig. 4a is a sectional view taken along the line 6a of Fig. 1, showing the manner of arranging a spring between the movable segment and filter shaft for urging rotation of the movable segment from its operative position, as in Fig. 3, to that of Fig. 2;

Fig. 5 illustrates diagrammatically a film television transmitter and the manner of arranging the color filter with movable segment in relation to the scanning cathode-ray tube;

Fig. 6 is a diagrammatic plan view illustrating an embodiment of direct pickup television transmitting apparatus and tube employing a filter drum with a movable segment, in accordance with the invention;

Fig. '7 is a front view of the apparatus of Fig. 6 showing the filter drum at rest with the movable segment thereof rotated to its inoperative position;

Figs. 8 and 9 are plan and front views, respectively, of a form of conical filter with movable segment, and an associated cathode-ray receiver tube, in accordance with the invention; and

Fig. 10 shows the movable segment of the filter rotated to its open or inoperative position out of the light path to expose the luminescent screen of the tube to direct view.

Referring to Fig. 1, the rotatable color-filter disk In is arranged in operative relation with a television receiver cathode-ray tube l I, so that the plane of the color-filter disk I is closely adjacent that of the face and luminescent screen l2 of the tube II with the axis of symmetry of the tube II and the rotating shaft [3 upon which the color-filter disk I0 is mounted, in parallel relation.

The multiple-unit filter disk Ill consists of two units, the first l4 being fixedly mounted on the shaft l3 and rotatable therewith. The second filter unit l5, a segment, is arranged on the shaft l3, so that it may be rotated thereon with respect to the first unit ll.

The shaft I3 is driven by the motor IS in proper synchronism with respect to the reproduced images on the screen l2, so that the different color filters of the units l4 and I are correctly associated successively with their respective images.

The filter disk I0 may be of the type described in my U. S. Patent No. 2,304,081 and means may be employed including the motor NS for maintaining proper synchronism and for automatically permitting a change of the phase of the rotating filter ID, in accordance with the inventions of U. S. Patents Nos. 2,329,194 and 2,319,789.

There is fixedly arranged on the shaft l3 a collar I! having a notch or a sharply defined indentation I8, which in conjunction with a springpressed detent [9 forms a detent-catch which is adapted to arrest and stop rotation of the shaft l3 and the filter l0 thereon when the motor I6 is deenergized, as will be described hereinafter in connection with Fig. 4.

The second unit or segment l5 of the filter I0 is provided with a spring 20 aflixed to the shaft l3 and which tends to rotate the segment IS on the shaft 13 with respect to the first filter unit l4 so that when rotation of the shaft I3 is arrested and stopped, by the detent-catch l9, [8, the first filter unit 14 is brought to rest in a predetermined position in relation to the face of the tube H and its luminescent screen l2.

Fig. 2 shows the filter ID at rest in the predetermined position effected by the detent-catch l9, l8, with the second filter unit or segment 15 rotated with respect to the first filter unit l0 out of the light path to and from the face of the tube 1 l to expose the luminescent screen l2 thereof to direct view through the uncolored transparent portion or aperture of the first filter unit M. The rotation of the segment i5 on the shaft l3 may be effected wholly by gravity or by grav ity assisted by the action of the spring 28, or wholly effected by the spring 20.

It will be observed from Fig. 2 that in the rotated or inoperative position of the second unit or segment of the filter In that the color-filter areas thereof overlay color-filter areas of the first unit Hi. A pin 25 serves as a, convenient stop for the segment l5 in the position in which the screen 12 of the tube H is exposed to direct view. In rotation the driving pin 26 contacts an edge of the second filter unit or segment l5, as shown in Fig. 3, whereupon the two filter units are driven in unison, the second by the first, and the several color-filter areas of the filter in pass successively across the light path to and from the image area 21' of the luminescent screen l2, in proper synchronism with the filter at the transmitter and in proper phase so that each filter is associated with its respective image,

The arrangement of the color-filter areas shown in Figs. 2 and 3 hereof are those of Fig. 3 of my Patent No. 2,304,081 and comprise two sets of three different color-filter areas, red, blue and green, respectively, in that order. As shown in Fig. 3, the different color-filter areas are, respectively, B1, B1, G1, and R2, B2, G2. With this arrangement and as shown in Fig. 2, the colorfilter areas R2 and B2, are a part of the second unit or segment l5 and in the rest position overlay the color-filter areas G2 and R1, respectively.

In Fig. 3, the driving pin 26 is shown as havin been rotated through the arc :c-y, whereupon it engages the edge of and drives the second filter unit IS in unison with the first filter unit l4.

Referring now to Fig. 4 the shaft I3 is shown in its arrested position efiectively stopped against rotation by the detent-catch l9, l8. The solenoid plunger magnet 30 connected in circuit relation with the motor is and voltage source 3|, is deenergized when the switch 32 is opened to stop the motor. Thus, when the switch 32 is opened the plunger 33 is released permitting the spring urged detent l9 to press against the collar I'l until the notch I8 is engaged by the detent l9 whereupon rotation of the shaft 13 and motor I6 is arrested.

Since the filter I0 is fixedly mounted on the shaft IS the angular position of the notch IS on the collar Il may be adjusted by rotating the collar and then fixing it on the shaft l3, so that the filter when arrested in its rotation by the detent-catch l9, I8, is stopped in the predetermined position wherein the transparent or aperture portion of the first filter unit II is so related to the image area 21 as to expose it to direct view as soon as the second unit or segment 15 rotates to its inoperative position, as shown in Fig. 1.

It will be understood that the circuit arrangement of Fig. 4 is schematic and that the switch 32 may be actuated in any desired manner separately or in conjunction with the operation of other controls of the television apparatus and the circuits thereof.

" of the storage or any other Fig. 4a shows one type of spring 29 connected to the shaft l3 providing one manner of urging separate rotation of the second filter unit l5 as the filter I comes to rest. Other types of springs or other means may be employed for this purpose, as will be understood, depending on the orientation of the axis of the shaft 3 and the amount of separate rotation of the second unit l5 desired in relation to the first unit l4.

Fig. 5 shows a television transmitter arrangement employing an intermittently moving film 48 advanced by appropriate intermittent filmdriving mechanism, not shown. The film-gate 4| exposes one film frame. The frame in the gate 4| is illuminated by a suitable projection-arc source 42 and condenser lenses 43. Images on the film frames in the film-gate 4| are projected by the lens 44 to the mosaic 45 of the scanning device 46, which may be a cathode-ray transmitter tube appropriate type.

If a cathode-ray tube of the storage type is used it is desirable to project the film image onto the mosaic 45 during the blanking period only. Therefore, a flashing shutter 41 driven by motor 48 is provided. A multiple-unit color filter 49 with movable segment 50 of the type of Figs. 1 and 2, is disposed in the light path from the film-gate 4| to the mosaic 45 of the cathode-ray tube scanning device 46.

The motor 48 serves to advance the film 40, drive the flashing shutter 41 and rotate the multiple-unit color filter 49. In this arrangement mechanical clutch means. not shown, may be employed to release the motor 48 from driving connection with the color filter 49. Thereupon, the color filter 49 may be manually rotated to a rest position wherein the transparent or aperture portion of the first unit 55 when the second unit or movable segment 58 is rotated to the inoperative position, exposes the mosaic 45 directly to light from the film-gate.

Since television film-transmitter apparatus is attended by skilled operators and rapid changeover from color to black and white transmission, or vice versa, is rarely required, there is little need for providing automatic arresting and positioning of the filter unit with respect to the cathode-ray tube mosaic.

The tube 45 is provided with suitable scanning means, not shown, including an electron scanning beam for scanning the image area of the mosaic 45 in horizontal and vertical directions.

In Figs. 6 and 7 a direct pick-up tube 55 and color-filter drum 56 are employed. Light rays from an object field 51 are collected by lens 58 and enter the open end 59 of the filter drum 56. Inside the filter drum 56 a mirror 69 is positioned to divert the light rays through the filters GI located on the peripheral surface of the drum, and to the image receiving area 62 of the scanning device 55 which may be of the storage tube type or any other appropriate electron tube pick-up device. The tube 55 illustrated is of the so-called Orthicon type and includes an electron gun 64, deflecting plates 65, vertical deflecting coils 66 and axial field coil 61. The horizontal deflecting plates 65 and vertical deflecting coils 66 are energized by suitable high-frequency and low-frequency wave generators, as indicated.

The filter drum 56 contains six color filters arranged alternately around and forming the peripheral surface thereof and comprises two sets of red, green and blue filters denoted R, G and B, as in Fig. 7. Narrow strips of metal 69 are provided between adjacent filter segments formdrive the same in unison ing boundaries between adjacent filter segments.

The filter drum 55 is mounted upon and rotated by the shaft 18 which in turn is driven by the motor 1|. The arrangement of Fig. 4 may be utilized to provide means for arresting rotation of the shaft 19 and filter drum 56, so that the filter drum may come to rest in a predetermined position with relation to the image recording area 62 of the tube 55.

The multiple-unit filter drum 56 as best shown in Fig. 7 is provided with a movable portion or segment 12 which may be separately rotated about the shaft 18 with respect to the first or fixed unit portion 13. A curved slot 14 at the periphery of the filter drum 56 provides a guide within which the color-filter segment 12 may freely move.

Since the filter drum 56 may be brought to rest s described above by means of the expedient of Fig. 4, the segment 12 will thereupon rotate to the position shown in Fig. 7, exposing the image area 62 directly to light in the path including the lens 58 and mirror 60.

When the motor 1| is again started to drive the shaft 10, the end 15 of the curved slot 14 will engage the movable filter segment 12 and with the first unit 13, so that the different color-filter areas R, G, B, are interposed successively in the light path to the image area 62. When the filter drum 56 is brought to rest as described, the color-filter areas of the second unit 12 overlay color-filter areas of the first unit 13, as illustrated in Fig. 7.

In Figs. 8-10 the cathode-ray receiver tube 9| has a bulbous portion 82, and an elongated neck portion 83. The fluorescent screen is on the inner surface of the envelope at the face 84. The rectangle represents the image area on which images are successively reproduced by a cathode ray beam from electron gun 86 deflected so as to scan the area 85 preferably in a plurality of side by side lines at field scanning frequency by horizontal deflecting plates 81 and by vertical deflecting plates 88, energized from separate appropriate sources, not shown, but well understood. The rotating color filter 89 comprises a conical frame having a plurality of color-filter areas 90 arranged on the conical surface as shown, two sets of red, green and blue (R, G, B) being provided.

The color filter 89 is arranged to'be rotated by the shaft 9| driven by a suitable motor 92 energized from a voltage source.

The cathode-ray tube 8| is disposed partially within the conical surface with its image area 85 closely adjacent the inner surface of the color filter 89, so that as the filter is rotated on its shaft 9| by the motor 92 the different color-filter areas 90 pass successively across the light path to and from the image area 85 with the boundaries between the filter areas 90 traversing the image area 85, preferably in substantially the low-frequency direction.

The construction of the multiple-unit color filter 89 is as shown in Fig. 10. It comprises a first segment or unit 93 and a second segment or unit 94 hinged at 95 on the first unit 93, so that the second unit 94 may be moved outwardly on its hinge 95 to expose the face 84 of the tube 8| and the image area 85 thereof to direct view. Suitable catches 96 are provided on the first unit 93, so that the second unit 94 when closed on its hinge to form a. conical surface with the first unit 93, will be maintained in its operative or 7 closed position during rotation with the first unit 98.

The arrangement of Figs. 8-10 requires the operator of a television receiver to manually adjust the position of the second filter unit 94 when the motor 82 is disconnected from its voltage supply source to view the area 85 directly for the reception of images in "black and white. For this reason its use may not be preferred in home television receivers.

In the event different scanning rates, etc., are employed for color and black and white at the transmitter, it will be necessary to provide at a receiver appropriate circuits and arrangements whereby either color or black and white" video signals may be employed to reproduce the respective television images on the same cathode-ray receiver tube image area. Thus, in deenergizing the motor driving the multiple-unit color filter to bring the filter to rest as herein described for the purposes of the invention the manipulation of a switch Or other means controlling operation of the motor and color filter may be employed to effect the necessary switching to permit of reception of the differently scanned black and whi images.

The improved multiple-unit color filter and its combination with an electronic scanning device may be modified without departing from the gist and scope of the invention as those skilled in the art will recognize. Therefore, only such limitations as may be imposed by the pertinent prior art should be considered in relation to the appended claims.

I claim:

1. In television apparatus, in combination with means for scanning an image area, a composite movable color filter disposed in operative relation with said image area and having a plurality of difierent color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, a portion of said filter areas being mounted separately from the remainder and adapted and arranged for separate rotational movement out of said light path when the filter is at rest.

2. In television apparatus, in combination with means for scanning an image area, a movable color filter disposed in operative relation with said image area and having a plurality of different color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, said filter having a portion of said filter areas adapted and arranged for separate movement, and means for automatically moving said portion of the filter areas out of said light path when the filter is brought to rest.

3. In television apparatus, in combination with means for scanning an image area, a movable color filter disposed in operative relation with said image area and having a plurality of diiferent color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, said filter having a portion of said filter areas adapted and arranged for separate movement, spring means for automatically moving said portion of the filter areas out of said light path when the filter is brought to rest, and engaging means fixed with respect to said filter adapted and arranged to mechanically engage said portion upon movement of said filter to drive said portion in unison therewith.

4. In television apparatus. in combination with 8 means for scanning an image area, a composite rotatable color filter of the disk type disposed in operative relation with said image area and having a plurality of difierent color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, certain of said filter areas being mounted separately from the remainder and adapted and arranged for separate rotational movement out of said light path when the filter is brought to rest.

5. In television apparatus, in combination with means for scanning an image area, a composite rotatable color-filter drum disposed in operative relation with said image area and having a plurality of different color-filter areas disposed around the peripheral surface thereof and adapted to pass successively across the light path to and from said image area when said filter is in motion, certain of said filter areas being mounted separately from the remainder and adapted and arranged for separate rotational movement out of said light path when the filter is brought to rest.

6. In television apparatus, in combination with means for scanning an image area, a composite rotatable color filter of conical form disposed in operative relation with said image area and having a plurality of different color-filter areas disposed around the peripheral surface thereof and adapted to pass successively across the light path to and from said image area when said filter is in motion, certain of said filter areas being mounted separately from the remainder and adapted and arranged for separate hinged movement out of said light path when the filter is brought to rest.

7. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about the axis of rotation thereof, comprising a first unit containing certain of said filter areas and adapted to be driven about said axis and a second unit containing certain other of said filter areas and arranged on said axis in separately movable relation with respect to both said first unit and the axis, said first unit being adapted and arranged to drive said second unit about said axis during rotation of the filter, said units rotating in unison being adapted to provide a symmetrical succession of said color-filter areas across a light path.

8. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about the axis of rotation thereof, comprising a first unit containing a first portion of said filter areas and adapted to be driven about said axis, a second unit containing a second portion of said filter areas arranged on said axis in separately movable relation with said first unit, and means for effecting limited relative movement of said units about said axis when the filter is brought to rest, said units when rotating in unison being adapted to provide a symmetrical succession of said color-filter areas across a light path.

9. A color television multiple-unit rotatable color filter of the disk type having a plurality of different color-filter areas disposed about the axis of rotation thereof, comprising a first unit containing a first portion of said filter areas and adapted to be driven about said axis, a second unit containing a second portion of said filter areas arranged on said axis in separately movable relation with said first unit, said first umt being adapted and arranged to drive said second unit during rotation of the filter, and means for effecting limited relative movement of said units about said axis when the filter is brought to rest, said units when rotating in unison being adapted to provide a symmetrical succession of said color-filter areas across a light path.

10. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about the axis of rotation thereof, comprising a first segment unit containing a first portion of said filter areas, a second segment unit containing a second portion of said filter areas and being separately movable with respect to said first segment unit, and means for effecting limited movement of one of said units relative to the other when the filter is brought to rest, said segments when rotating in unison being adapted to provide a desired succession of color-filter areas across a light path and when at rest to overlay at least in part.

11. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about the axis of rotation thereof, comprising a first segment unit containing a first portion of said filter areas, a second segment unit containing a second portion of said filter areas and being separately movable on said axis with respect to said first segment unit, said first segment unit being adapted and arranged to drive said second unit in unison therewith to provide a desired succession of color-filter areas across a light path, said second segment being adapted and arranged to overlay said first segment at least in part when the filter is brought to rest to provide an unobstructed light path.

12. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about the axis of rotation thereof, comprising a shaft adapted to be driven about said axis, a first segment unit containing a first portion of said filter areas and fixedly mounted on said shaft for rotation thereby, a second segment unit containing a second portion of said filter areas mounted on said shaft for separate rotation with respect to both the shaft and the said first segment unit, said second segment being adapted and arranged to be driven by said first segment during rotation of said shaft and to overlay said first segment at least in part when the shaft is brought to rest.

13. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about the axis of rotation thereof, comprising a shaft adapted to be driven about said axis, a first unit containing a first segment portion of said filter areas and a transparent portion adapted to pass white light, said first unit being fixedly mounted on said shaft for rotation thereby, a second unit containing a second segment portion of said filter areas mounted on said shaft for separate rotation with respect to both the shaft and the first unit, said second unit being adapted and arranged to be driven by said first unit in unison therewith to provide a desired succession of color-filter areas across a light path, said second segment portion of filter areas being adapted and. arranged to overlay said transparent portion of the first unit during rotation of the shaft and to overlay at least in part the first segment portion of filter areas when the shaft is brought to rest.

14. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about a horizontal axis of rotation thereof, comprising a shaft adapted to be driven on said horizontal axis, a first unit containing a first segment portion of said filter areas and an aperture segment adapted to pass white light, said first unit being fixedly mounted on said shaft for rotation thereby, means for arresting rotation of said shaft and first unit at a preselected position of said aperture segment when the shaft is not being driven, a second unit containing a second segment portion of said filter areas mounted on said shaft and arranged for separate rotation with respect to both the shaft and the first unit, said second unit being adapted and arranged to be driven by said first unit in unison therewith to provide a desired succession of color-filter areas across a light path, said second segment portion of filter areas being adapted and arranged to overlay said aperture segment during rotation of the shaft and to overlay at least in part the first segment portion of filter areas when the shaft is brought to rest.

15. A color television multiple-unit rotatable color filter having a plurality of different colorfilter areas disposed about a vertical axis of rotation thereof, comprising a shaft adapted to be driven on said vertical axis, a first unit containing a first segment portion of said filter areas and an aperture segment adapted to pass white light, said first unit being fixedly mounted on said shaft for rotation thereby, means for arresting rotation of said shaft and first unit at a preselected position of said aperture segment when the shaft is not being driven, a second unit containing a second segment portion of said filter areas mounted on said shaft for separate rotation with respect to both the shaft and the first unit, said second unit being adapted and arranged to be driven by said first unit in unison therewith to provide a desired succession of color-filter areas across a light path, spring means for effecting limited movement of said second unit on said shaft with respect to said first unit when the shaft is brought to rest, to a position in which the second segment portion overlays at least in part the first segment portion of filter areas and unobstructing said aperture segment to thereby permit the passage of white light.

16. In television apparatus, in combination with means for scanning an image area, a mul tiple-unit movable color-filter disposed in operative relation with said image area and having a plurality of different color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, a first unit of said filter providing both a first portion of said filter areas and an aperture portion adapted to pass white light, a second unit of said filter providing a second portion of said filter areas and arranged to be separately movable with respect to said first unit, said second unit being adapted and arranged to overlay said aperture portion of the first unit when the filter is in motion, and to overlay at least a portion of the color-filter areas of the first unit when the filter is at rest to unobstruct said aperture segment and permit passage of white light to and from said image area.

17. In television apparatus, in combination with means for scanning an image area, a multiple-unit rotatable color filter disposed in operative relation with said image area and having a plurality of different color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in mo-- tion, a first unit of said filter providin both a first portion of said filter areas and an aperture portion adapted to pass white light, a second unit of said filter providing a second portion of said filter areas and arranged to be separately movable with respect to said first unit, said first unit being adapted and arranged to drive said second unit, said second unit being adapted and arranged to overlay said aperture portion of the first unit when the filter is in motion, and to overlay at least a portion of the color-filter areas of the first unit when the filter is at rest to unobstruct said aperture segment and permit passage of white light to and from said image area.

18. In color television receiving apparatus, in combination with means for scanning an image area, a composite movable color filter disposed in operative relation with said image area and having a plurality of different color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, a portion of said color-filter areas being mounted separately from the remainder and adapted and arranged for separate rotational movement out of said light path when the filter is at rest, and means for arresting movement of said filter while continuing the operation of said scanning means, whereby said apparatus may be employed to reproduce pictures which may be viewed unobstructed by said color-filter areas.

19. In color television transmitting apparatus, in combination with means for scanning an image area, a composite movable color filter disposed in operative relation with said image area and having a plurality of different color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, a portion of said color-filter areas being mounted separately from the remainder and adapted and arranged for separate rotational movement out of said light path when the filter is at rest, and means for arresting movement of said filter while continuing the operation of said scanning means, whereby said apparatus may be employed alternatively to transmit pictures either in color or in black and white.

20. In television apparatus, in combination with means for scanning an image area, a movable color filter having a plurality of different color-filter areas disposed in operative relation with said image area and adapted to pass continuously and successively across the light path to and from said image area when in motion, a portion of the areas of said filter being adapted and arranged for separate movement relative to the others, a rotatable shaft for driving said color filter, electric motor means for rotating said shaft, a source of voltage for energizing said motor, electric switch means for controllin the application of voltage from said source to the motor, means for arresting rotation of said shaft and movement of said color filter at a predetermined position of said color filter in relation to said image area when the electric motor is not energized from said source, and means including the effect of arresting said color-filter movement for moving said separately movable portion of said color-filter areas out of the said light path as the filter comes to rest.

21. In television apparatus, in combination with means for scanning an image area, a movable color filter having a plurality of different color-filter areas disposed in operative relation with said image area and adapted to pass continuously and successively across the light path to and from said image area when in motion, a portion of the areas of said filter being adapted and arranged for separate movement relative to the'others, a rotatable shaft for driving said color filter, electric motor means for rotating said shaft, a source of voltage for energizing said motor, electric switch means for controlling the application of voltage from said source to the motor, mechanical means adapted to be electromagnetically released for arresting rotation of the shaft and movement of said color filter at a predetermined position of said color filter in relation to said image area when the electric motor is not energized from said source, and means including the effect of arresting said color-filter movement for moving said separately movable portion of said color-filter areas out of said light path as the filter comes to rest.

22. In television apparatus, in combination with means for scanning an image area, a movable color filter having a plurality of different color-filter areas disposed in operative relation with said image area and adapted to pass continuously and successively across the light path to and from said image area when in motion, a portion of the areas of said filter being adapted and arranged for separate movement relative to the others, a rotatable shaft for driving said color filter, electric motor means for rotating said shaft, a source of voltage for energizing said motor, mechanical means adapted to be electromagnetically released for arresting rotation of the shaft and movement of said color filter at a predetermined position of said color filter in relation to said image area when the electric motor is not energized from said source, and electric switch means for simultaneously controlling the energization of the motor and the release of said shaft rotation arrestin means, and means including the effect of arresting said color-filter movement for moving said separately movable portion of said color-filter areas out of the said light path as the filter comes to rest.

23. In television apparatus, in combination with means for scanning an image area, a shaftdriven multiple unit rotatable color filter having a plurality of different color-filter areas disposed in operative relation with said image area and adapted to pass continuously and successively across the light path to and from said image area when in motion, a first unit of said filter providing both a first portion of said filter areas and a portion adapted to pass white light arranged and adapted to be driven by the shaft, a second unit of said filter providing the second portion of said filter areas arranged and mounted so as to permit of separate rotation thereof with respect to said first unit and about the shaft, an electric motor for driving the said shaft and first portion of the filter, said first portion of the filter adapted and arranged to drive and rotate the said second portion in unison therewith, a source of voltage for energizing the motor, means for arresting rotation of the shaft and stopping movement of the said first unit of the filter in predetermined relation with said image area so that white light may pass to and from said area when the motor is not energized from said source, and means including the efiect of arresting movement of said first unit for rotating said second unit on the shaft with respect to said first unit so that its filter areas overlay filter areas of said first unit.

24. In television apparatus, in combination with means for scanning an image area, a multiple-unit rotatable color filter disposed in operative relation with said image area and having a plurality of different color-filter areas adapted with means for scanning 13 to pass successively across the light path to and from said image area when said filter is in motion, a rotatable shaft for driving said color filter, a first unit of said filter providin both a first portion of said filter areas and a transparent portion adapted to pass white light, said first unit being fixed to said shaft for rotation thereby, a second unit of said filter providing a second portion of said filter areas mounted on said shaft for separate rotation with respect to the shaft and first unit, and a driving member fixed with said first unit and positioned and adapted to engage said second unit to rotate the units in unison with the second portion of the filter areas overlaying the transparent portion of the first unit, said second unit being spring biased to rotate the second portion of the filter areas away from said transparent portion when the filter is at rest to thereby provide an unobstructed path for the passage of light to and from said image area.

25. In television apparatus, in combination an image area, a mulfilter disposed in operative relation with said image area and having a plurality of difi'erent color-filter areas adapted to pass successively across the light path to and from said image area when said filter is in motion, a rotatable shaft for driving said color filter, a first unit of said filter providing both a first portion of said filter areas and a transparent portion adapted to pass white light, saidfirst unit being fixed to said shaft for rotation thereby, a second unit of said filter providing a second portion of said filter areas mounted on said shaft for separate rotation with respect to the shaft and first unit, a driving member fixed with said first unit and positioned and adapted to engage said second unit to rotate the units in unison with the second portion of the filter areas overlaying the transparent portion of the first unit, said second unit being spring biased to rotate the second portion of the filter areas away from said transparent portion when the filter is at rest to thereby provide an unobstructed path for the passage of light to and from said image area, and

' a stop for limiting the relative rotation of the second unit when the filter is at rest to a position with the filter areas of the second unit at least partially overlaying the filter areas of the first unit.

PETER C. GOLDMARK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

